Tab for easy-open ecology end

ABSTRACT

When the improved tab is lifted by its lifting end, its opening end ruptures a scored line defining a panel, and this opens the container. The tab is retained to the container by a flap extending from the opening end toward the lifting end and including an affixing portion which is riveted to the container. After the container has been opened, the lifting end of the tab is depressed toward the end of the container. In prior art tabs, flexing of the flap occurred at a first bending region adjacent the affixing portion during both the lifting and depressing motions. In contrast, in the present invention the flap is shaped to provide a second bending region adjacent the openind end, in addition to the first bending region adjacent the affixing portion. When the lifting end is lifted, the improved tab flexes in the first bending region, and when the lifting end is depressed, the improved tab flexes in the second bending region. In this manner the flexing is shared between the first and the second bending regions.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to an easy-opening container and morespecifically, to an improved retained tab affixed to the end wall of thecontainer for opening it.

2. THE PRIOR ART

Easy-opening containers typically include a tap permanently joined to atear strip, the latter being separable from the can top to provide anopening. Typically, the top is ruptured along a continuous score lineand the tab and tear strip are removed as a unit and normally discarded.

The wide spread use of easy-opening containers has resulted in thelittering of beach and picnic areas by an accumulation of discardedpull-tabs and tear strips. These discarded items are difficult to cleanup because of their small size and because they are normally made ofaluminum and therefore cannot be collected by magnetic means.

The can industry has responded to this ecological problem by developinga number of ingenious easy-opening containers in which the tab and tearstrip are permanently retained to the can even after it has been opened.Typical cans of this type are are disclosed in: U.S. Pat. No. 4,030,631,issued June 1, 1977, to Brown; U.S. Pat. No. 4,024,981, issued May 24,1977, to Brown; and U.S. Pat. No. 4,015,744 issued Apr. 5, 1977, toBrown.

Some states have ecology laws which forbid the use of a closure thatseparates from the can in the opening movement. The recently developedecology cans disclosed in the above patents comply fully with such statelaws. However, it has been found that the tabs can be broken off fromthe cans by successive flexing movements, and a few sightings of suchbroken-off tabs have been reported. In view of this continuinglittering, some state regulatory agencies are imposing more stringentrequirements upon the cans. To meet these requirements, it will benecessary for the tab to be retained to the can even after beingsubjected to a number of flexing cycles. Thus, an urgent need exists foran easy-open can having a tab which can withstand a number of flexingcycles without breaking off.

One approach to increasing the flexure endurance of the tabs isdisclosed in columns 12 and 13 of U.S. Pat. No. 3,967,752, issued July6, 1976, to Cudzik. Cudzik discloses a composite tab which includes aninsert of a dead soft aluminum alloy. This insert, which has superiorflexural endurance continues to retain the tab to the can even after thebody of the tab, which is made of a stiff aluminum alloy, has failed dueto flexural fatigue.

Because of its composite structure, the tab disclosed by Cudzik requirestooling for producing it which is substantially more expensive than thetooling required to produce the improved tab of the present invention.

The limited flexural endurance of the tabs disclosed in the patentsissued to Brown referred to above is inherent in their structure. Inthose tabs, the repeated flexing is localized along a line adjacent therivet by which the tab is affixed to the can end. Successive flexingcycles cause the material in this area of localized flexing to workharden, becoming brittle and breaking there. Except for its limitedflexural endurance, the tab disclosed in the Brown patents referencedabove is very attractive because of its unitary structure and relativelylow cost of production.

Thus, it appears that an urgent need exists in the can industry for aretained tab having a unitary structure and capable of withstanding anumber of flexing cycles.

SUMMARY OF THE INVENTION

It has been found that a minor but crucial improvement to the unitarytab can greatly increase the number of flexure cycles it can withstandwhile still remaining secured to the can end.

The improvement involves shaping the flap portion of the tab, whichpreviously failed under repeated flexing, in such a way as to avoidlocalized bending of the material. In a preferred embodiment, a secondbending region is produced so that the bending is distributed over alarger area. Accordingly, the angular deflection is reduced and thebending radius is increased, resulting in greater flexural endurance.

In a preferred embodiment, the width of the flap portion nearest theopening end of the tab is intentionally reduced to encourage bending inthat region, thereby generating a second region of bending spaced fromthe normal region of bending adjacent the attaching portion of the tab.

When improved in this manner, the unitary tab disclosed in the abovereferenced patents to Brown fills the need for a unitary tab havingincreased flexural endurance and which is inexpensive to produce.

The novel features which are believed to characterize the invention bothas to its structure and operation, together with further objects andadvantages, will be better understood from the following descriptionconsidered in connection with the accompanying drawings in which apreferred embodiment of the invention is illustrated by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a preferred embodiment of the improved tabof the present invention;

FIG. 2 is a cross-sectional elevation view in the direction A--A of FIG.1, showing the relationship of the tab of the preferred embodiment tothe end of the can while the can is in a sealed condition;

FIG. 3 is a cross-sectional elevation view in the direction A--A of FIG.1 showing the relationship of the tab to the end of the can immediatelyafter the seal has been "popped;"

FIG. 4 is a cross-sectional elevation view in the direction A--A of FIG.1, showing the relationship of the tab to the can end when the liftingend of the tab has been pulled upright to open the can;

FIG. 5 is a cross-sectional elevation view in the direction A--A of FIG.1 showing the relationship of the tab to the end of the can after thetab has been pushed toward the can end to prepare the can for use;

FIGS. 6-11 are cross-sectional elevation views in the direction A--A ofFIG. 1 and shown in sequence successive stages in the flexing of the tabof the prior art; and

FIGS. 12-17 are a series of cross-sectional elevation views in thedirection A--A of FIG. 1 and shown successive stages in the flexing of atab of the preferred embodiment.

DESCRIPTION OF THE PREFERREDEMBODIMENT

In the following detailed description of a preferred embodiment of theinvention, the terminology used will be compatible with that used inU.S. Pat. No. 4,030,631 issued June 21, 1977, to Brown, and like partswill be denoted by the same reference numerals.

Referring now to FIG. 1, in which a plan view of the easy-opening endstructure of the preferred embodiment is shown, an opening is formed inthe container when the tab 10 is used to fracture a scoreline 12 whichdefines a panel 14 in the end 16 of the container. In U.S. Pat. No.4,030,631, the panel 14 and the rivet 18 are unitary parts of the end16, while the tab 10 is a separate part retained to the end 16 by therivet 18. The structural details of the easy-open end, along with themethod of fabricating it and the manner in which it is used aredescribed in the above-referenced U.S. Pat. No. 4,030,631 which isincorporated herein by reference.

The tab 10 includes a lifting end 20, spaced leg members 22, 24, and anopening end 26. The spaced leg members 22, 24 are connected near thelifting end 20 by a web portion 28, which may include an indexing hole.The spaced leg members 22, 24 are formed of single-ply sheet metal andare curled for strength and for safety. The tab thus has a roughlyrectangular shape with the lifting end 20 opposite the opening end 26and with the leg member 22 opposite the leg member 24. A flap portion 30extends from the opening end 26 longitudinally toward the lifting end 20between the spaced leg members 22, 24. The flap 30 includes an affixingportion 32 spaced from the opening end 26 and including an aperture 34through which the rivet 18 passes to retain the tab 10 to the end 16. Aswill be described more fully below, the flap 30 includes a first bendingregion 36 extending laterally across the flap 30 adjacent the affixingportion of it and on the side of the aperture 34 nearest the opening end26. In accordance with the teaching of the present invention, the flap30 further includes a second bending region 38 adjacent the opening end26 and likewise extending laterally across the flap 30. in the preferredembodiment, the lateral edges 40, 42 of the flap determine its width atvarious locations in the longitudinal direction. In accordance with theteaching of the present invention, the width of the flap is varied alongthe length of the flap to define the first bending region 36 and thesecond bending region 38. In the preferred embodiment, the width of theflap in the second bending region is less than the width of the flap inthe first bending region.

Without departing from the teachings of the present invention, it ispossible to define first and second bending regions along the flap byincluding apertures located along the flap at selected regions. Suchapertures reduce the effective width of the flap in the region wherethey are located, so that bending of the flap can take place morereadily there, owing to the reduced stiffness of the flap structure atsuch regions. Thus, the word "width", as used in the presentdescription, should be understood to comprehend the concept of effectivewidth as discussed above.

FIG. 2 is a cross-sectional elevation view of the can end in thedirection indicated by the broken line A--A of FIG. 1. FIG. 2 shows therelation of the tab 10 to the end 16 when the container is in the sealedcondition before it has been opened.

FIGS. 3, 4 and 5 are views similar to FIG. 2 showing the interaction ofthe tab 10 with the end 16 at various stages in the process of openingthe container. In FIG. 3, the lifting end 20 as been pulled away fromthe end 16 as indicated by the arrow. This action brings the opening end26 of the tab 10 into contact with an underlying portion 44 of the panel14, which serves as the fulcrum of a class 2 lever, by means of whichthe rivet 18 and adjoining portion of the end 16 are lifted upwardly,causing a rupture 46 to occur at the score line 12 adjacent the rivet18. Once the rupture has begun, the panel 14 yields much more readily tothe force applied to it by the opening end 26 of the tab, so that thefulcrum of the lever becomes the rivet, and the lever operates as aclass 1 lever, the opening end 26 of the tab depressing the panel 14 tothe position shown in FIG. 4. FIG. 4 shows the relation of the parts atwhat is normally the extreme of the lifting motion. The score linedefining the panel 14 is not a closed figure in the preferredembodiment, so that when the stage shown in FIG. 4 has been reached, thepanel 14 remains attached to the end 16 by means of a small bridge 48,which retains the panel 14 to the end 16 thereby peventing litter andalso preventing the panel 14 from falling loosely into the container.

Although an opening has now been formed in the end 16 over the regionformerly occupied by the panel 14, it is normal in beverage cans tothereafter push the lifting end 20 of the tab toward the end 16 as shownin FIG. 5, so as to facilitate drinking directly from the container.During this motion, the panel 14 remains in the same position it had inFIG. 4.

The action of the flap 30 during the sequence shown in FIGS. 2-5 isparticularly noteworthy. From the initial position shown in FIG. 2, theflap 30 begins to wind around the adjoining portion 50 of the openingend 26, while experiencing a slight downward flexing with some bendingoccurring at the first bending region 36, as indicated in FIGS. 3 and 4.During those phases of the sequence, almost no flexing occurs in thesecond bending region 38. During the return motion shown in FIG. 5,notable flexing occurs in the second bending region 38, accompanied by amodest flexing of the first bending region 36 in the upward direction.To the extent that flexing occurs at the second bending region 38,flexing does not have to occur in the first bend-region 36. Thisillustrates one of the important teachings of the present invention,namely the benefit of distributing the flexing along the length of theflap 30 so as to avoid localized flexing.

It is believed that a cumulative work hardening effect takes place inthe bending regions each time they are flexed. In this regard, thepresent invention teaches the successive use of the first bending region36 and the second bending region 38 on the successive raising andlowering motions of the lifting end 20 respectively, so that after thefirst bending region 36 had become embrittled during the lifting motion,further flexing of the first bending 36 is avoided as much as possible,the flexing required during the downward motion of the lifting end 20takes place at the second bending region 38 which has not becomeembrittled.

Only two bending regions are used in the preferred embodiment to sharethe flexing that results from the first and second, raising andlowering, motions of the tab. However, the concept of the invention isbroader, comprehending shaping the flap portion of the tab specificallyto reduce localized bending of the material. Consistent with this broadconcept, various numbers of bending regions can be used in otherembodiments to distribute the bending along the flap.

This benefit of the present invention can be seen more clearly incomparison with the prior art. FIGS. 6 through 11 show successive stagesof the opening process for an end constructed according to the priorart, while FIGS. 12-17 show the action at corresponding stages for thetab of the present invention. FIGS. 6 and 12 show the initial positionin which the container is sealed. In FIGS. 7 and 13, the tab has beenlifted, rupturing the score line. In FIGS. 8 and 14, the process iscontinued with the panel 14 being depressed into the can. FIGS. 9 and 15shown the relative positions of the parts at the extreme positionreached in the lifting motion of the tab. It is noteworthy that to thispoint in the opening process, the amount of flexing and the location ofthe flexing are substantially the same for both the prior art tab andthe tab of the present invention. In each case some flexing has occurredin the first bending region 36 adjacent the rivet 18. The superiorflexing endurance of the tab of the present invention results from itsoperation during the return motion of the tab shown in FIGS. 10, 11, 16and 17. As seen in FIGS. 10 and 11, considerable reverse bending occursin the tab of the prior art at the first bending region 36, which isalready embrittled by the flexing that occurred during the initialmovement illustrated in FIGS. 6-9. Thus, during the completecontainer-opening sequence (FIGS. 6-11), the tab of the prior art isflexed twice in the first bending region 36, first in one direction andthen in the opposite direction.

In contrast, when the tab is constructed according to the preferredembodiment of the present invention, the flap 30 is bent only once atthe first bending region during the lifting motion illustrated in FIGS.12-15, with most of the flexing produced by the retun motion of FIGS. 16and 17 taking place in the second bending region 38, which has notpreviously been flexed and which therefore is not embrittled. Thus, itis seen that in the preferred embodiment, the flexing is distributedalong the length of the flap 30 so as to avoid localized flexing so faras possible. The superior flexural endurance of the tab of the presentinvention results from its structure which defines more than one bendingregion so that flexure of the flap is distributed and localized flexingis avoided. The tab of the present invention fills an urgent need in thecontainer industry for a retained-tab end having superior endurance torepeated flexing motions and which can be produced economically withexisting equipment.

The foregoing detailed description is illustrative of the preferredembodiment of the invention, but it will be understood that additionalembodiments will be obvious to those skilled in the art. The embodimentsdescribed herein together with those additional embodiments areconsidered to be within the scope of the invention.

What is claimed is:
 1. A tab of the type affixed to a can end foropening it and comprising:a unitary structure including a lifting end;an opening end opposite said lifting end and spaced from it; spaced legmembers connecting said lifting end and said opening end; and, a flapextending longitudinally from said opening end toward said lifting endbetween said spaced leg members, spaced from said spaced leg members andfrom said lifing end, including an affixing portion by which said flapis affixed to the can end, said affixing portion spaced from saidopening end, the width of said flap varying along the length of saidflap to define a first bending region extending laterally across saidflap adjacent said affixing portion and a second bending regionextending laterally across said flap adjacent said opening end, thewidth of said flap in said second bending region being sufficientlysmall relative to the width of said flap in said first bending regionthat after said lifting end has been pulled away from the can, therebyflexing said flap in said first bending region, when said lifting end issubsequently pushed toward the can end, said flap flexes in said secondbending region, whereby no part of said flap is flexed more than once assaid lifting end is pulled away from the can and then pushed backtowards its original position adjacent the can end.
 2. In a unitary tabof the type affixed to a can end for opening it and having a lifting endopposite an opening end, and having spaced leg members connecting theopposite ends, the improvement comprising:a flap extending from theopening end toward the lifting end between the spaced leg members,spaced from the spaced leg members and from the lifting end, andincluding an affixing portion by which said flap is affixed to the canend, said affixing portion spaced from the opening end, the width ofsaid flap increasing along the length of said flap between the openingend and said affixing portion so that flexing of said flap isdistributed along the length of said flap between the opening end andsaid affixing portion when the lifting end of the tab is first liftedaway from the can end and then pushed back towards it, whereby repeatedlocalized flexing is substantially avoided.
 3. The improvement of claim2 wherein said flap is generally tapered in width between the openingend and said affixing portion.
 4. The improvement of claim 2 whereinsaid flap is sufficiently narrow adjacent the opening end that after thelifting end has been pulled away from the can end thereby bending saidflap in a first bending region of it located adjacent said affixingregion, when the lifting end is subsequently pushed toward the can endsaid flap bends in a second bending region of it located adjacent theopening end. .Iadd.
 5. A tab for easy opening containers comprising atab body having means at one end particularly adapted for applying aninwardly directed rupturing pressure on the container panel when theopposite end is moved outwardly, said tab having a bendable mounting earpositioned intermediate its ends for connection to the end panel, andmeans providing a plurality of hinge axes on said ear for accommodatingshifting the bend of the ear from one axis to another attendant to backand forth bending movements of said tab and thus impeding fracture ofthe ear and thereby removal of the tab from the container. .Iaddend..Iadd.6. The invention according to claim 1 and said one end of the tabcomprising a nose portion having a non-work hardened section and atleast one of said hinge axes being located in said section. .Iaddend..Iadd.7. The invention according to claim 2 and said mounting ear havinga narrower than elsewhere width portion adjacent to said non-workhardened section. .Iaddend. .Iadd.8. The invention according to claim 1and said ear having side edges with at least one notch in each edgedefining at least one of said hinge axes. .Iaddend. .Iadd.9. Theinvention according to claim 5 and said notches each defined by an inneredge and said inner edges converging toward said one end of the tab..Iaddend. .Iadd.10. The invention according to claim 1 and said meanscomprising a portion at the forward end of the tab each sloping upwardlytoward said one end of the ear and adapted to ear during hingingmovement between the tab and ear. .Iaddend. .Iadd.11. The inventionaccording to claim 1 and said tab being made of thin one piece sheetmetal. .Iaddend. .Iadd.12. The invention according to claim 1 and saidtab being aluminum. .Iaddend. .Iadd.13. An easy opening container endwith nondetachable means for making an opening therethrough suitable forpouring comprising:A tab having work hardened means at one end forrupturing said end and a nonwork hardened section and having a liftportion at the other end for lifting the tab and pressing said one endagainst said container end, and attaching means on the container end andsaid tab for securing the tab to said container end and comprising asecuring lug on the tab, and at least one selected hinging axis ofconnection between the said lug and tab in a nonwork hardened section ofthe tab at said one end. .Iaddend. .Iadd.14. The invention according toclaim 11 and said tab having a central depressed body section and saidlug being cut from said body section. .Iaddend.